Positive displacement rotary vane engine

ABSTRACT

The present invention is an engine, which includes a positive displacement compression process, a variably fueled, continuous combustor and/or heat exchanger, and a positive displacement, work-producing expander. This arrangement avoids the traditional stochiometric mixture requirements utilized in spark-ignition based engines and the emission problems associated with diesel engines.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional of U.S. Non-Provisional PatentApplication Ser. No. 12/043,066, filed Mar. 5, 2008, which claims thebenefit of U.S. Provisional Patent Application Ser. No. 60/892,913,filed Mar. 5, 2007, the entireties of which are hereby incorporatedherein by reference.

TECHNICAL FIELD

The present invention relates generally to engines. More particularly,this invention relates to positive displacement rotary vane engines.

BACKGROUND OF THE INVENTION

Premixed and direct-injection spark-ignition piston engines operating onthe Otto cycle and direct injection engines operating on the dieselcycle represent the bulk of known engines used for motor vehicles. Theseengines are popular for a variety of reasons but, primarily, they arewidely used because they offer reasonable efficiencies for a wide rangeof power settings. One major disadvantage for spark-ignition engines isthat they must operate in a mode in which the ratio of the fuel mass tothe air mass in the engine at the combustion stage is nearstoichiometric. Thus, to operate at partial power, the engine must bethrottled, whereby the pressure on the intake side must be deliberatelyreduced in order to limit air mass flow rate. This effectively limitsthe compression ratio and, in turn, the efficiency of the engines. Thisfact is the basis for the success of the hybrid-electric propulsionsystem.

The direct-injection spark-ignition and diesel engines are not aslimited by this requirement but these two types of engines havesignificant emissions problems. The problem of varying the mixture ratioaway from stoichiometric is solved using high turn-down ratio combustorsin Brayton cycle engines based on gas turbine technology. This ispossible because the combustion process occurs in a separate physicalarea of the engine from the compression and expansion, allowing for onlypart of the air to be burned in combination with the fuel in a highlycontrolled way. Having a separate physical area where combustion takesplace allows the power levels to be controlled by varying only the fuelflow rate to the combustor. The disadvantage to running the Braytoncycle engines at partial power is explained by the fact that known axialflow compressor and turbine systems are inefficient at off-designoperating points.

Another disadvantage of conventional piston engines is that the air isported to the combustion chamber through valves, which limit the abilityof the engine to breathe efficiently and introduce pumping losses evenwith wide open throttle settings.

To combat these problems, many efforts have been made to developsuccessful high volumetric flow rate positive displacement compressorsof the rotary vane type. Previously known engines of the rotary vanetype have substantially depended on intermittent spark-ignition and/orfuel injection in a small volume for combustion. This inherently limitsthe performance in the same way that piston engine performance islimited by combustion stoichiometry.

Additionally, the sealing of rotary vane devices for high temperatureapplications such as combustion engines has eluded inventors to date andexcessive wear has hampered the success of known rotary vane devices ofall types. In order to create a successful rotary vane engine, positivesealing of the vanes must occur along the outer edge of each vane, alongthe sides of each vane, along the base area of each vane and between therotor and the case. Without proper sealing, adequate compression andexpansion cannot take place. Additionally, the high wear ratesassociated with the centrifugal forces of known rotary vane engines mustbe reduced for longevity of the device.

Thus it can be seen that needs exist for improvements to combustionengines and particularly those of the rotary vane type. Additionally, itcan be seen that needs exist for rotary vane combustion engines thateffectively seal the compression and expansion cavities while reducingcomponent wear, such that an extended service rotary vane engine can beimplemented. It is to the provision of these needs and others that thepresent invention is primarily directed.

SUMMARY OF THE INVENTION

In example forms, the present invention is an engine that employs apositive displacement compression process, a variably fueled, continuouscombustor (such as a combustor used in a gas turbine) and/or a heatexchanger, and a positive displacement, work-producing expander. Thisarrangement avoids the stochiometric mixture requirements withtraditional spark-ignition engines based on the entire engine air massflow rate and the inefficiencies of off-design compressor and turbineperformance. Additionally, this arrangement is not compression ratiolimited as spark-ignition engines are. Furthermore, the engine of thepresent invention significantly reduces engine emissions typical withthe operation of diesel engines. Example embodiments of this engine asdescribed herein are in the form of a sealable rotary vane device.

In one aspect, the present invention relates to an improvement to arotary vane internal combustion engine having an external housing and aneccentrically mounted rotor therein. The rotor is operable forrotational movement within the housing to define compression andexpansion cavities. The improvement to the engine includes a pluralityof blades in mechanical communication with the rotor and extendingradially therefrom. The blades are expandable for engagement with atleast one interior confronting face of the external housing.

In another aspect, the present invention relates to a rotary vane engineincluding a cowl that defines an internal chamber and a rotor rotatablymounted with the internal chamber. The rotor includes a plurality ofradially configured splines spaced to define slots between successivesplines. The engine also includes a plurality of rotary blades and eachblade is received in a corresponding one of the slots. The rotary bladesare in sliding engagement with the splines. The rotary blades areexpandable.

In another aspect, the present invention relates to a rotary vane engineincluding an external housing defining a hollow chamber therein and arotor eccentrically mounted within the chamber. The rotor includes aplurality of rotary blades extending radially therefrom. The engine alsoincludes a race that is substantially contained within the rotor. Therace is in mechanical engagement with at least a portion of the bladesto limit the radial extension of the blades in relation to the rotor.

In still another aspect, the present invention relates to a rotary vaneengine including a cowl defining a hollow chamber therein and a rotoreccentrically mounted within the chamber. The rotor includes a pluralityof rotary blades extending radially outwardly therefrom for sealingengagement with an interior confronting face of the cowl. At least aportion of the interior face of the cowl defines a substantiallyexponential curvature.

In yet another aspect, the present invention relates to a continuouslycombusting rotary vane engine comprising a cowl and a rotor rotatablymounted within the cowl. The rotor includes a plurality of radiallymounted blades configured to compress a working fluid from the rotor.The engine also includes a combustor in fluid communication with thecowl to receive compressed working fluid from the rotor. At least aportion of the compressed working fluid is mixed with a fuel source toform a mixture and the mixture is substantially continuously combustedwithin the combustor.

In another aspect, the present invention relates to a heat poweredrotary vane engine including a cowl and a rotor rotatably mounted withinthe cowl, the rotor having a plurality of radially mounted bladesconfigured to compress a working fluid. The engine also comprises a heatexchanger in fluid communication with the cowl to receive compressedworking fluid from the rotor. Energy is transferred from the heatexchanger to at least a portion of the compressed working fluid receivedtherein. Optionally, the heat exchanger is a solar thermal collector.

Is still another aspect, the present invention relates to a rotary vaneengine including an external housing defining a hollow chamber therein,a first rotor eccentrically mounted within the chamber, and a secondrotor eccentrically mounted within the first rotor. The second rotorincludes a plurality of rotary blades extending radially therefrom. Theblades extend outwardly through the first rotor to maintain sealingengagement with a confronting interior face of the external housing.

These and other aspects, features and advantages of the invention willbe understood with reference to the drawing figures and detaileddescription herein, and will be realized by means of the variouselements and combinations particularly pointed out in the appendedclaims. It is to be understood that both the foregoing generaldescription and the following brief description of the drawings anddetailed description of the invention are exemplary and explanatory ofpreferred embodiments of the invention, and are not restrictive of theinvention, as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically shows an example embodiment of a rotary vane enginecycle according to the present invention.

FIG. 2 is cross sectional plan view of a rotary vane engine according toan example embodiment of the present invention.

FIG. 3 is an exploded perspective view of a rotor used in conjunctionwith the engine of FIG. 2.

FIG. 4 is a side view of the rotor of FIG. 3, shown mounted with anoutput gear.

FIG. 5 is a perspective view of a rotor spline used with the rotor ofFIG. 3.

FIG. 6 is a perspective partial cut-away view of the rotor of FIG. 3, anexample blade race, and a fixed shaft according to an example embodimentof the present invention.

FIG. 7 is a perspective view of the blade race and fixed shaft of FIG.6.

FIG. 8 is a perspective view an example embodiment of a rotary bladeused in conjunction with the engine of FIG. 2.

FIG. 9 is a perspective partial cut-away view of the rotor, blade race,and fixed shaft of FIG. 6, shown mounted with the blade of FIG. 8.

FIG. 10 shows a prior art sealing configuration between an enginehousing and rotary blade.

FIG. 11 shows another prior art sealing configuration between an enginehousing and rotary blade.

FIG. 12 shows an example configuration according to the presentinvention of an optimal arrangement for sealing a blade against anengine housing.

FIG. 13 is a mathematical depiction used to configure the optimalarrangement between the blade and engine housing.

FIG. 14 is a blown-up perspective view of the blade sealing surfaces ofthe blade of FIG. 8.

FIG. 15 is an alternative embodiment of a rotary blade used inconjunction with the engine of FIG. 2.

FIG. 16 is a perspective partial cut-away view of the engine of FIG. 2,shown without the combustor.

FIG. 17 is a cross sectional plan view of a solar powered rotary vaneengine according to an alternate example embodiment of the presentinvention

FIG. 18 is a side view of a dual bodied rotor assembly according toanother example embodiment of the present invention.

FIG. 19 is a plan view of the dual bodied rotor assembly of FIG. 18shown without the bearings or synchronizing gears.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

The present invention may be understood more readily by reference to thefollowing detailed description of the invention taken in connection withthe accompanying drawing figures, which form a part of this disclosure.It is to be understood that this invention is not limited to thespecific devices, methods, conditions or parameters described and/orshown herein, and that the terminology used herein is for the purpose ofdescribing particular embodiments by way of example only and is notintended to be limiting of the claimed invention. Also, as used in thespecification including the appended claims, the singular forms “a,”“an,” and “the” include the plural, and reference to a particularnumerical value includes at least that particular value, unless thecontext clearly dictates otherwise. Ranges may be expressed herein asfrom “about” or “approximately” one particular value and/or to “about”or “approximately” another particular value. When such a range isexpressed, another embodiment includes from the one particular valueand/or to the other particular value. Similarly, when values areexpressed as approximations, by use of the antecedent “about,” it willbe understood that the particular value forms another embodiment.

In general, the engine of the present invention includes a plurality ofvane-type blades that are radially positioned around an offset axis, insuch a way as to allow movement in and out of a slotted rotor as theblades are rotated thereabout. The blade tips ride against and arebiased towards a variable radius outer housing or cowl, wherein variablevolume gas cavities are formed between the blades and the outer housing.The rotation of the blades provides for compression and expansion of airby their circular movement against the variable radius outer surface.The compression ratio of the various example embodiments as describedbelow is determined primarily by the distance between successive bladesand by the precise positioning of the intake port and the combustorports. The example embodiments shown and described below represent asubstantially constant volume combustion device and have been found toexhibit a compression ratio of approximately 15:1; however, theinvention also includes embodiments exhibiting higher or lowercompression ratios.

With specific reference now to the drawing figures, the operationalengine cycle of an engine 10 according to an example embodiment of thepresent invention is shown in FIG. 1. Generally, the engine 10 of thepresent invention includes an outer housing or cowl 20, anexpansion/compression cavity 30, an internal rotor 40, and an externalcombustor 50. In example embodiments, rotation of the rotor 40compresses fresh air, or alternate working fluid, brought in through anintake port 60 and into the compression side of theexpansion/compression cavity 30 a and deposits the same into thecombustor 50. Compressed air is deposited into the combustor 50 througha compression port 80. Upon entering the combustor 50, fuel isintroduced into a portion of the air stream at high pressure. Theresulting fuel/air (fuel/working fluid) mixture is ignited in thecombustor 50 and the ensuing combustion that takes place rapidly heatsthe air before it is reintroduced into the expansion side of thecompression/expansion cavity 30 b for expansion, before ultimately beingrejected to the external environment through an exhaust port 70. Theheated air is reintroduced into the expansion cavity 30 b via anexpansion port 85. The rapid expansion of the air after combustioninduces rotation of the rotor 40 to complete the engine cycle of thepresent invention. As shown in the drawing figures, example embodimentsof the engine 10 comprise a single rotor 40 that is used for bothcompression and expansion. Alternatively, the engine 10 can utilize twoor more rotors 40. Depending on the particular locations that the air isported into and out of the combustor 50 from the compression/expansioncavity 30, example embodiments of the engine 10 can be operated onvarious engine cycles such as: a constant volume combustion process suchas the Otto Cycle and/or the Atkinson Cycle, a constant pressurecombustion process such as the Brayton Cycle, or the engine can beoperated on a cycle in-between the two as the Diesel cycle is oftenmodeled.

In example embodiments of the present invention the combustor 50 of theengine 10 only allows for a fraction of the air to be burned whilemaintaining combustible mixtures necessary for continuous combustion. Inthis embodiment, the combustor 50, as shown schematically in FIG. 2,includes a ducting system 52 and overall shape, such as an oval, circle,ellipse etc. (but not limited to such), to allow for continuouslyrecirculating air, fuel and combustion products. This design permits avariable level of fuel injection through a ported cylindrical device.The primary consideration for the recirculating design is to ensurecontinuous combustion of the fuel at high turn-down ratios with minimumemissions. For example, as compressed air is brought into the combustor50, the ducting system 52 routes a portion of the air away from a fuelinjecting source 54 through a duct 53, such that the intake air issegregated. By segregating the air, not all of the intake air isimmediately combusted (and not all of the air will necessarily becombusted) and is circulated through the combustor 50. In exampleembodiments, fuel is introduced into the combustor 50 through ahigh-pressure fuel injector 54, which directly injects fuel into atleast a portion of the intake air stream from the compression port 80.An igniter 56, such as for example a spark or glow plug, is located inproximity to the fuel injector 54 to ignite the fuel/air mixture. Inpreferred example embodiments, the igniter 56 is only needed duringstart-up to initially combust the fuel/air mix, as continual combustiontakes place within the combustor 50. Delivery of compressed air into thecombustor 50 via the compression port 80 (and expanding gases beingdelivered back into the expansion/compression cavity 30) further enablescontinuous combustion in preferred example embodiments, as compressionand expansion is permitted to continuously occur within thecompression/expansion cavity 30 rather than intermittent compression,ignition, and expansion typical with known engines. Because air isintroduced into the combustor 50 at constant volume and pressure, a userneed only reduce the amount of fuel injected into the combustor 50 toreduce overall engine output. Most known engines operating on the Ottocycle require a user to reduce (throttle) both the air and fuel that isdelivered to the combustion chamber in order to reduce engine output,which reduces both the compression ratio and efficiency of the engine.Additonally, the continuous combustion that occurs within the combustor50 significantly reduces harmful emissions produced by the engine 10,when compared to the emissions produced by known spark-ignition anddirect injection engines. Specifically, the combustor 50 has a largerrelative volume and higher resonance times than known spark-ignition anddirect injection engines. Furthermore, the recirculation of combustionproducts within the combustor 50 minimizes CO, NO, and soot emissions.In alternate example embodiments, the igniter 56 ignites the fuel/airmix intermittently, such that semi-continuous or intermittent combustionoccurs within the combustor 50.

A more detailed image of an example embodiment of the engine 10 isdepicted in FIG. 2. As seen therein, the rotor 40 and the cowl 20 areaxially offset, such that the volume of the compression/expansion cavity30 is variable throughout the compression/expansion cycle. The rotor 40is further comprised of a plurality of individual pie-shaped wedges orsplines 100 and a pair of rotor side plates 44 that are mated to eachside of the splines 100 to keep the splines in proper alignment asdepicted in FIGS. 2-4. The rotor side plates 44 are coaxially alignedwith the splines 100 and each spline can be mated thereto with boltsand/or nuts, or other mechanical fasteners or attachment means. Inexample embodiments, the rotor side plates 44 include a plurality ofbolt holes 46 that correspond to a plurality of bolt holes 47 in eachspline for receiving a bolt therethrough, such that the two can berigidly secured together. For example, bolt holes 46 a, 46 b, 46 c inthe rotor side plates 44 correspond to bolt holes 47 a, 47 b, 47 c inthe splines 100, as shown in FIG. 3. The bolt holes 46, 47 can be tappedto receive threaded bolts/screws or can be bored as desired.Alternatively, the rotor side plates 44 can be welded in whole, or incombination with other fasteners, to the splines 100. Each spline 100further includes at least one, and preferably a series of, concentricgrooves 102 positioned near the radial end of the spline, as shown inFIG. 5. The concentric grooves 102 are adapted to receive compressionseals or rings to prevent blow-by from reaching the interior of therotor 40 and seal the rotor against the cowl 20. As such, the rotor 40is fully sealable.

Referring again to FIG. 2, the rotor 40 further includes a rotating hub42, which rotates about a fixed shaft 90. In example embodiments, thehub 42 is disengaged from the fixed shaft 90, such that a gap existsbetween same. In such embodiments, bearings 92 (FIGS. 4 and 16) can beincluded between the hub 42 and the cowl 20 to keep the rotor 40 inproper alignment within the cowl. In alternate embodiments, the hub 42comprises a hollow sleeve that is rotatably coupled to the shaft 90, andcan include one or more bearings (not shown), such as ball, sleeve, orother bearings, to reduce friction between the hub and shaft.Alternatively, lubricant such as oil and/or grease, can be appliedbetween the hub 42 and fixed shaft 90 to reduce mechanical wear andfriction between the same.

The rotor 40 is adapted to slidably receive a plurality of expandablevanes or blades 110 between the plurality of splines 100 as shown inFIG. 2. The blades 110 are received in gaps or slots 45 located betweensuccessive splines 100 and are free to slide within the slots, such thatthe radial extension of the blades from the splines is variable.Generally, the blades 110 extend outwardly from the splines 100 tomaintain sealing contact with the confronting inner face of the cowl 20.In example embodiments, the number of blades 110 corresponds to thenumber of splines 100, such that the rotor 40 includes an equal numberof blades and splines. Alternative embodiments of the engine 10 caninclude more blades 110 than splines 100, or vice versa, as desired by auser. It has been found that the compression ratio of the engine 10increases as the number of splines 100 and blades 110 increases. Atrelatively high rotating speeds, the blades 110 in example embodimentsof the rotary vane device shown in the drawing figures can be pressedagainst the outer housing 20 by centrifugal forces much larger than theforce that is needed for creating a seal between the two. In fact, suchforces are responsible for the relative inefficiencies of known rotaryvane engines, as the forces cause rapid wearing of the rotary vanes.Therefore, the rotor 40 of the present invention also houses an internalblade guide or race 120, to guide the sliding movement of the blades 110within the blade slots 45. In general, the race 120 limits the radialdistance each blade 110 extends from the rotor 40, which will beexplained in detail below. As shown in FIG. 5, each spline 100 includesa cutout 104 for receiving the race 120 therethrough, such that the raceis contained within the splines. However, in preferred embodiments therace 120 is not in direct engagement with the splines 100, as betterseen in FIG. 6, which demonstrates the relative relationship between therotor side plates 44, splines, and race.

Rather than engaging the splines, the race 120 is fixedly positionedwithin the cowl 20 and is anchored to the fixed shaft 90; therelationship between the race and shaft can be seen in FIG. 7. The fixedrace 120 can be rigidly coupled to the shaft 90 with splines, keys,cotters, or other conventional fasteners, or the race can be permanentlymated to the shaft through welding. Alternatively, the race 120 and theshaft 90 can be cast as one piece. In example embodiments, the shaft 90is rigidly coupled to the housing or cowl 20, to ensure that the shaftand race 120 are fixedly positioned within the same. As shown in bothFIGS. 6-7, the race 120 includes a lip or blade guide surface 122 forcontacting a portion of the blade 110 thereon. Each blade 110 includes ablade collar 112, as can be seen in FIG. 8, for rotatable and/orslidable engagement along the blade guide surface 122. Additionally,each blade 110 includes a narrow cutout 114 that extends above the bladecollar 112 and around the collar's distal edge for receiving the race120 and the blade guide surface 122 therethrough. FIG. 9 depicts a blade110 in engagement with the blade guide surface 122 of the race 120. Itcan be seen that the blade collar 112 is pressed against the inside edgeof the blade guide surface 122 (and is firmly held there by centrifugalmotion when in operation) and that the race and guide surface fit intoand through the cutout 114. Referring back to FIG. 2, it can be seenthat as the rotor 40 and blades 110 rotate within the cowl 20, the bladecollar 112 maintains contact with the blade guide surface 122, such thatthe radial extension of the blades from the splines 100 varies as theblades circumnavigate the race 120. For example, the blades 110 reachmaximum radial extension (fully extended position) from the splines 100just as each blade passes the exhaust port opening 70, and are minimallyextended (or are flush with the rotor) as the blades pass thecompression port 80 (retracted position).

In preferred embodiments of the present invention, the curvature of thecowl 20 is in the shape of an exponential curve, as seen in FIG. 2.While other embodiments can utilize various elliptically or otherwiseshaped cowl designs, it has been found that engine performance isoptimized when the cowl 20 is shaped as an exponential curve.Additionally, it has been found that engine performance is optimizedwhen the shape of the race 120 is substantially geometrically similar(same shape or similar shape, but different scale) to the curvature ofthe cowl 20, or vice versa, as shown in FIG. 2. Specifically, sealingbetween the blades 110 and the cowl 20 can be maintained over extendedservice cycles when the blades are forced to follow a race 120 having anexponential curve coupled with a substantially geometrically similar, orapproximately similar, curve for the cowl. Known rotary vane typeengines are inefficient and often fail after few service cycles due tothe lack of an effective sealing surface between the blades and housing.For example, most known rotary vane engines depend upon blade tipsealing arrangements as shown in FIGS. 10-11. FIG. 10 depicts a squaretipped blade riding against a curved surface. This arrangement has beenunsuccessful because an effective seal cannot be created between theblade and the housing due to the minimal contact area between the same.Additionally, the minimal contact area results in a high rate of wearthat quickly reduces the efficiency of an engine employing thisarrangement. FIG. 11 depicts an improved arrangement (over thearrangement depicted in FIG. 10), wherein the blade tip is rounded toreduce the amount of wear. However, because the contact area between theblade tip and housing is still relatively small, blow-by and compressionlosses result in significant engine inefficiencies. Instead, it has beenfound that seals between the rotary blades and the housing offer bettersealing qualities and improved lubrication characteristics when intimatecontact is effected between two nearly flat surfaces, as opposed tothose known seals between a substantially curved surface and a nearlyflat surface. Additionally, it has been found that a blade tip having arelatively large flat contact area that is angled to match the surfacecontour of the cowl provides for maximum sealing (and engine)efficiency, as depicted in FIG. 12.

The optimal shape for the curvature of the cowl 20 and race 120 can bemathematically determined with the following analysis and reference toFIG. 13. The distance from the origin of the rotating motion of theblade to the curving cowl wall is “R” and the angle between a flat bladetip and an otherwise perpendicular blade tip surface is 13″. As theblade moves through a differential angle Δθ, the change in the radialdistance between the origin of blade motion and the surface of the cowl,ΔR will be:

ΔR=R(Δθ)(tan β)

For differential changes in the angle θ, this equation can be rewrittenas:

dR=(tan β)R(dθ)

For intimate contact between the blade tip and the cowl surface to bemaintained, the angle β will be constant not only for the fixed geometryblade but also for the surface upon which it slides. Taking βto beconstant and separating the variables yields:

$\frac{R}{R} = {( {\tan \; \beta} ){\theta}}$

Integrating this equation from a reference starting value of R_(o) atθ=0 gives:

ln R|_(r) _(o) ^(R)=(tan β)θ

or

R=R_(o)e^((tan β)θ)

Hence the most ideal shape for sealing between the blade tip and cowlwith a fixed geometry blade is exponential. To demonstrate the optimalcurve shape in another way, the sealing of the blade tips against thecowl can be optimized by recognizing that a short line segment at apractically perpendicular radial line can slide in nearly intimatecontact with a cowl containing the rotating vanes if the shape of thecowl is an exponential curve described by the equation:

r=r₀e^(kθ)

where “r” is the radius of the curve at a given angle θ from a referenceline, “r_(o)” is the reference radius (approximately the radius of therotor), and “k” is a small constant determined based on desired engineflow rates and mechanical considerations. In addition, the relationshipbetween the curvature of the race 120 and the curvature of the cowl 20can be represented as:

r_(cowl)=r_(race)+d

wherein the radius of the cowl at any given point is equal to the radiusof a corresponding point on the race plus some constant “d” representingthe radial distance between the corresponding points. Therefore, it ispreferred, but not required, that race 120 and cowl 20 followcorresponding exponential curves to optimize blade sealing capacity andengine performance.

In order for the blades 110 to optimally seal against the curvature ofthe cowl 20 as the blades rotate through both the compression andexpansion cycles, the tip of each blade 115 is fitted with a blade tipseal 130, as better seen in FIG. 14. In example embodiments, each bladetip seal 130 is comprised of a dual headed tip having two flat surfaces132, 134 for intimate engagement with the cowl 20. As each blade rotatesfrom the exhaust port 70 towards the compression port 80, the flatsurface 132 is in engagement with the cowl 20, and when the blade movesfrom compression back into expansion, the opposite flat surface 134engages the cowl. In this manner, a flat surface of the blade tip seal130 is in constant engagement with the cowl 20 at all times duringexpansion and compression. Alternatively, the blade tip seal 130 can berounded or include a single flat surface. In still other embodiments,the blade tip seal 130 can comprise more than two flat surfaces asdesired.

Returning to FIG. 8, in example embodiments, the sides of each blade 110are fitted with first and second side seals 140 to seal each bladeagainst the sides of the cowl 20 to prevent blow-by and/or compressionloss. Generally, the side seals 140 are as thick as the blades 110, asdepicted in the drawing figures, but in alternate embodiments the sideseals are a fraction of the blade thickness. The side seals 140 can berigidly coupled to the blade tip seal 130 through any number ofconventional joints, such as a bridle joint, dovetail joint, lap joint,T-joint, mortise and tenon joint, and/or any other conventional methodof joining the same. In preferred example embodiments, a bridle joint142 is used to couple the side seals 140 to the blade tip seal 130. Inother embodiments, the side seals 140 and blade seal 130 can be formedas a unitary part, separately or in conjunction with the blade 110.

During operation, the internal components of the engine 10 expand due tothe heat from internal combustion, including the cowl, theexpansion/compression cavity 30 and the blades 110. Unfortunately, oncetight tolerances between these components at startup grow significantlyas the components are exposed to high heat. Known rotary vane engineshave been unsuccessful in resolving these changes in tolerances, whichtypically result in increased engine wear and large inefficiencies dueto compression losses. The present invention solves this problem byengineering the blades to expand to maintain sealing across a range ofthermal expansion and contraction. One such embodiment of an expandableblade is seen in FIG. 8, wherein the expandable blade 110 is comprisedof three main components: two blade halves 116, 117 and at least oneexpansion wedge 150 therebetween. Alternatively, the blade 110 can bedivided into thirds or fourths or fifths, etc. and two or more expansionwedges can be used as desired. In depicted example embodiments, the twohalves 116, 117 are interlocked together through the use of at least onetongue and groove joint 118. In alternate embodiments, the two halvescan be coupled with additional joints to interlock the same and/or othertypes of conventional fasteners, such as clips, hooks, etc., orconventional joints can be utilized. In example embodiments, theexpansion wedge 150 is positioned within a recess 152 into the face ofthe two blade halves 116, 117, such that the expansion wedge is flushwith the top surface of the blade halves, as shown in the drawingfigures. The wedge 150 also includes a protrusion 154 that is receivedby a complementary recess 156 in the blade 110 to further provide africtional force to retain the wedge therein. In example embodiments,the wedge 150 is triangular, wherein the narrowest angle of the triangleis directed towards the blade tip 115 and the wider end of the triangleis directed towards the root of the blade. In preferred embodiments, twoor more wedges 150 can be used per blade 110. In still otherembodiments, the blade body 110 can be comprised of a unitary unit.However, regardless of the particular embodiment used, as the enginecomponents are exposed to heat from the internal combustion, the cowl 20begins to expand. This expansion causes gaps to occur between the bladetip seal 130, side seals 140, and the expanding cowl, such thatefficiency losses would occur without the expansion capabilities of theblade 110. The centrifugal forces that the blade 110 is subjected to innormal operation, biases the expansion wedge 150 radially outwards(towards the cowl 20), such that the triangular wedge drives the twohalves 116, 117 incrementally apart and permits the blade 110 to expandwidthwise and maintain a seal against the cowl 20.

Numerous other embodiments of expanding blades can be used with thepresent invention, such as the alternative blade design depicted in FIG.15. The main segments of the blade 210 are shown in this figure. In thisparticular embodiment, there are five different components that can beedge fitted using a tongue and groove arrangement surrounded by thethree seal sections (130, 140) in a similar arrangement as describedabove. The five components include three blade components, 212, 214, and216 and further include two wedge components 250 and 252. Using thisarrangement, the side surfaces can independently expand at separaterates around the flow path and they can be non-parallel, such that theblade and swivel/pivot slightly. This allows for more versatile sealingarrangements but increases blade complexity. In another exampleembodiment the blades 110 can be engineered to expand by constructingthe blades out of a material that has a different thermal rate ofexpansion than the cowl 20, such that as the cowl and blades are heated,the blades expand to fill in the gap created by the thermal expansion ofthe cowl. However, nothing herein is intended to limit the present theinvention to a particular expanding blade design, as numerous bladeembodiments can be conceived based on the expanding blade conceptdisclosed herein to prevent blow-by and compression losses during normaloperating conditions.

A sectional view of an example engine according to the present inventionis depicted in FIG. 16, showing the components (without the combustor)interconnected within the cowl 20. It can be seen that at least one gear160 is connected to the rotor hub 42 for outputting power to be used asdesired. In alternate embodiments, the rotor hub 42 can be directlycoupled to a transmission system or gear box for use in an automobile orother vehicle. Although a method of operation has already been describedabove, it can be better seen how an example engine 10 according to thepresent invention operates in FIG. 16. The outer housing or cowl 20defines a chamber, which houses the eccentrically mounted rotor 40. Therotor 40 includes the plurality of splines 100 radially configured andspaced apart to define slots 45 between successive splines. Theplurality of rotary blades 110 are received in the corresponding slots45, wherein the blades are permitted to slide within the slots, suchthat the blades can be radially extended or retracted in respect to therotor 40. The radial extension of the blades 110 is limited by the race120, which includes the blade guide surface 122. Each blade 110 includesa blade collar 112 to engage the blade guide surface 122 and limit theradial extension of the blades. The blades 110 include a tip sealingsurface 130 and side sealing surfaces 140, which engage confrontingfaces of the cowl 20, to seal the blades against the cowl. The race 120permits the blades 110 to engage the interior face of the cowl 20, suchthat blade sealing can be maintained, but prevents the blades from beingsubjected to high wear forces. As the rotor 40 and blades 110 arerotated about the fixed shaft 90, intake air is compressed and depositedinto the combustor 50 (not shown) where the air is mixed with a fuelsource and combusted. Once combusted, the exhaust is received into theexpansion side 30 b of the expansion/compression cavity 30, where theexhaust is allowed to expand and further drive the rotation of the rotor40. The at least one gear 160 is coupled to the rotor 40 to output powergenerated by the engine 10.

In example embodiments of the present invention, the engine componentsare generally made from 4140 hardened steel and the wear surfaces arecoated with nitrites to prolong engine use. The blade seals 130, 140 areformed from a bronze alloy and the combustor is formed from stainlesssteel. In other embodiments, the engine components can beinterchangeably formed from stainless steel, hardened steel, chromiumalloyed steel, titanium, aluminum, cast iron, high temperature alloys,composite or thermoplastic materials, nickel, and/or other various typesof metals and metal alloys. Nothing herein, is intended to limit thepresent invention to being constructed from a particular type(s) ofmaterial and the materials listed above are for example purposes only.

In an alternate embodiment of the present invention, the engine 10 isimplemented in the form of a dual rotary vane stage in which partialcompression in the first stage is followed by cooling in a specificallydesigned intercooler such as those found on some turbocharged pistondesigned automobile engines. The final stage would compress the cooledair further before introducing it into a combustor. The output gasesfrom the combustor would then drive the two stages in series. The twostages would be tied together in a direct drive arrangement tomechanically ensure flow continuity and thus efficiency of compression.

In another alternate embodiment of the present invention, the engine 10′can include a solar thermal collector 50′ instead of a combustor asdescribed above, as depicted in FIG. 17. Other than the solar thermalcollector 50′ the remainder of the engine 10′ comprises the same orsimilar components as described in the example embodiments above, andare designated with a prime designation. As shown in FIG. 17, air orother working fluids are compressed in gas cavities 30′ formed betweenthe blades 110′ and the cowl 20′ by the rotation of the rotor 40′. Theworking fluid is ported into the solar thermal collector 50′ through thecompression port 80′, where the working fluid is heated. The solarthermal collector 50′ can utilize energy collected from the sun to heatthe working fluid deposited therein. The heated working fluid can thenbe ported back into the rotor 40′ through the expansion port 85′, wherethe working fluid is allowed to expand and power the rotor. In exampleembodiments, the working fluid is atmospheric air. Alternatively, theworking fluid can be argon (for greater efficiency), or other fluidtypes as desired by a user.

In other alternate embodiments, the combustor can be replaced with anyknown heat exchanger to deliver energy to heat the working fluid. Assuch, the heat exchanger can be powered by coal fuel, nuclear energy,solar power, etc.

In still another alternate example embodiment, the present inventionincludes an engine 310 having a dual bodied rotor 340 that iseccentrically mounted within a cowl 320, as seen in FIGS. 18-19. Therotor 340 is comprised of two rotor bodies, an inner rotor 342 and anouter rotor 344. In example embodiments, the cowl 320 and rotor bodies342, 344 are substantially circular in shape. Other shapes, such aselliptical, exponential, etc. can be used as desired. However, in thepresent embodiment utilizing circular shaped rotor bodies and cowl 320,the blades 410 remain in substantially perpendicular sealing engagementwith the cowl, such that a sealing arrangement is maintained. In fact, across-section of the cowl 320, as seen in FIG. 18, can be substantiallycircular in shape. The present embodiment can be utilized with, orwithout, a race as desired. To maintain sealing between the blades 410and the cowl 320, at least two synchronizing gears 322, 324 can beutilized between the two rotor bodies 342, 344, as shown in FIG. 18. Inaddition, the blades 410 can pivot at one or more pivot points, as seenin FIG. 19 to maintain a substantially perpendicular sealing arrangementbetween the cowl 320.

While the invention has been described with reference to preferred andexample embodiments, it will be understood by those skilled in the artthat a variety of modifications, additions and deletions are within thescope of the invention, as defined by the following claims.

1. A rotary vane engine comprising: an external housing defining ahollow chamber therein; a rotor eccentrically mounted within thechamber, the rotor having a plurality of rotary blades extendingradially therefrom; a race substantially contained within the rotor, therace being in mechanical engagement with at least a portion of theblades to limit the radial extension of the blades in relation to therotor.
 2. A rotary vane engine of claim 1, wherein the engine furthercomprises a fixed shaft coupled to the housing.
 3. A rotary vane engineof claim 2, wherein the race is rigidly coupled to the fixed shaft. 4.The rotary vane engine of claim 3, wherein the rotor is operable forrotational movement about the fixed shaft and race.
 5. The rotary vaneengine of claim 1, wherein the race limits the radial extension of theblades from a retracted position to an extended position.
 6. The rotaryvane engine of claim 5, wherein the race comprises a blade guide surfaceto engage the blades.
 7. The rotary vane engine of claim 6, wherein theblades comprise a blade collar for engagement with the blade guidesurface.
 8. A rotary vane engine comprising: A cowl defining a hollowchamber therein; and a rotor eccentrically mounted within the chamber,the rotor having a plurality of rotary blades extending radiallyoutwardly therefrom for sealing engagement with an interior confrontingface of the cowl; wherein at least a portion of the interior face of thecowl defines a substantially exponential curvature; wherein the enginefurther comprises a race substantially contained within the rotor, therace being in mechanical communication with at least a portion of theblades to limit the radial extension of the blades in relation to therotor, and wherein the race is substantially elliptical in shape.
 9. Acontinuously combusting rotary vane engine comprising: a cowl; a rotorrotatably mounted within the cowl, the rotor having a plurality ofradially mounted blades configured to compress a working fluid; and acombustor in fluid communication with the cowl to receive compressedworking fluid from the rotor; wherein at least a portion of thecompressed working fluid is mixed with a fuel source to form a mixtureand the mixture is substantially continuously combusted within thecombustor.
 10. The continuously combusting rotary vane engine of claim9, wherein the combustor is externally located with respect to the cowl.11. The continuously combusting rotary vane engine of claim 10, whereinthe working fluid is ported from the cowl to the combustor.
 12. Thecontinuously combusting rotary vane engine of claim 11, wherein themixture is heated by combustion and the resulting heated mixture isported back into the cowl where it is operable upon the rotor.
 13. Thecontinuously combusting rotary vane engine of claim 9, wherein thecombustor includes at least one duct to segregate the compressed workingfluid before the compressed working fluid is mixed with the fuel source.14. The continuously combusting rotary vane engine of claim 9, whereinthe working fluid is atmospheric air.
 15. A heat powered rotary vaneengine comprising: a cowl; a rotor rotatably mounted within the cowl,the rotor having a plurality of radially mounted blades configured tocompress a working fluid; and a heat exchanger in fluid communicationwith the cowl to receive compressed working fluid from the rotor;wherein energy is transferred from the heat exchanger to at least aportion of the compressed working fluid received therein.
 16. The heatpowered rotary vane engine of claim 15, wherein the heat exchanger is asolar thermal collector.
 17. A rotary vane engine comprising: anexternal housing defining a hollow chamber therein; a first rotoreccentrically mounted within the chamber; and a second rotoreccentrically mounted substantially within the first rotor, the secondthe rotor having a plurality of rotary blades extending radiallytherefrom; wherein the blades extend outwardly through the first rotorto maintain sealing engagement with a confronting interior face of theexternal housing.